Does my crabapple tree with spotted leaves and black fruit have a disease?
Question:
I have a 23-year-old crabapple tree. This past summer and fall the leaves were spotted with black and brown. It only produced small shriveled black fruit. Is there a disease I should be treating for?
Answer:
Last year was a challenge for all kinds of fruit-bearing trees in Maine, due to 1) late killing frosts last spring that destroyed a great deal of flower bud tissue that had begun to flush, and 2) an inordinately wet season that drove fungal infections like leaf spot for numerous species across the state. Without seeing the symptomatic leaves, it’s tough to diagnose what might be going on, but if you haven’t had trouble with the tree in the past, it was probably suffering those unusual conditions along with many other Maine trees.
With a more normal spring temperature cycle this year and (ideally) a drier season, we are hoping to see a rebound in 2024. If you see signs of the leaf spot and/or shriveled fruit return, please reach back out to us with photos and we can get a more definitive diagnosis for you. You can always mitigate these conditions by properly pruning the tree to promote plenty of air flow through the canopy, cutting out damaged/diseased tissue, and promptly removing any leaf litter or detritus on the ground (where spores might overwinter).
If you are concerned about the lichen growth on your tree, you can be reassured that it’s almost always harmless to the tree. Read more about lichens on bark in this great Univ of NH Extension response.
Happy gardening.